1. Field of the Invention
The present invention relates to a box-type terminal whose contact portion which is brought into contact with a mating terminal is in a square cylindrical shape.
2. Description of the Related Art
FIG. 5 shows a conventional terminal 1 described in Japanese Utility Model Unexamined Publication No. Sho. 54-133392. In this case, a blanking press is used to form the terminal 1 out of a conductive metal sheet. The terminal 1 has a clamping portion 2 which clamp s an electric wire (not shown), a connecting portion 3 which clamps the conductor of the electric wire so as to conduct itself relative to the electric wire, and a contact portion 4 into which a mating terminal (not shown) is inserted, these portions being integrally form ed.
In the contact portion 4, side plate portions 6, 6 are extended upward from both sides of a base plate portion 5 and the upper portions of the side plate portions 6, 6 are coupled together by an upper plate portion 7 to form a square cylindrical shape. Moreover, a coupling portion 8 for coupling the upper portions of the side plate portions 6, 6 is provided on the side of the connecting portion 3. The coupling portion 8 is formed with an elastic contact leaf 9 having elasticity as it is sloped downward, and the elastic contact leaf 9 is extended downward under the upper plate portion 7 whereby to creep into the interior of the contact portion 4.
A contact surface 10 is formed by striking out the base plate portion 5 in a portion corresponding to the elastic contact portion 9 in the base plate portion 5. The contact surface 10 is stamped to a rectangular shape having a length of L1 with the whole length having a uniform width of W.
As shown in FIG. 6(a), a mating terminal 11 is inserted from the leading end of the contact portion 4 of the terminal 1 and when the elastic contact portion 9 presses the mating terminal 11 thus inserted against the contact surface 10, the contact surface 10 becomes conducted relative to the mating terminal 11.
When the mating terminal 11 or a jig (not shown) bumps against the contact surface 10 in the above-described terminal as shown in FIG. 6(a), the contact surface 10 is deformed as shown in FIG. 6(b) and this is problematical in that the conduction performance is impaired because of the deformation. As shown in FIG. 6(c), moreover, the contact surface 10 tends to bend even at the time of normal contact and consequently the conduction performance is also impaired because the bending causes the contact surface 10 not to be brought into stable contact with the mating terminal 11.